Non Clustered Index in SQL Server

A Non Clustered Index in SQL Server stores the index structure separately from the data physically stored in a table. The Microsoft allows you to create almost 999 non clustered indexes per table. The non clustered index in SQL Server is useful to improve the query performance. Say, you want to retrieve employees by their sales (which is a regular report), then you can use this on Sales to retrieve the records quickly.

Let me show you what will happen if you create a Non clustered Index in SQL Server. For example, if you had a Customer table with the following records. Assume Customer key is Primary key (means Clustered), but you require to retrieve records by yearly Income.

In this situation, you have to create a non clustered index on the Yearly Income column. It will store the Yearly income records in separate locations along with the row address. When you ask for customer records whose Income = 79000. First, it will look for 79000 in the second table, and after finding the record, it will check the row address. Second, it will retrieve record (from the First table) at that row address

Two Tables Data 22

In this chapter, we will show you how to create and delete a non clustered index in SQL Server using Transact Query, and Management Studio

Table Data with Index 1

Create Non Clustered Index in SQL Server

This example explains to you how to add to an existing table. And the syntax is:

CREATE NONCLUSTERED INDEX Index_Name
ON Table_Name (Column_Name(s) ASC/DESC)

It will create SQL Non Clustered Index on Yearly Income Column present in the Customer record table

-- Create Non Clustered Indexes
CREATE NONCLUSTERED INDEX IX_CustomerRecord_YearlyIncome
ON CustomerRecord ([Yearly Income] ASC)
Messages
--------
Command(s) completed successfully.

Let me use the sp_helpindex stored procedure to check the indexes on the Customer Record table.

EXECUTE SP_HELPINDEX CustomerRecord

As you can see, the Yearly Income column has Non Clustered index.

EXECUTE SP_HELPINDEX to View Indexes 3

You can also use SP_HELP stored procedure in SQL Server to check the same.

EXECUTE SP_HELP CustomerRecord

It displays all the information about the table.

EXECUTE SP_HELP to get Table Information 4

Create Composite Non Clustered Index in SQL Server

You to create non clustered index on multiple columns. So, you can point the same to Multiple columns. In this example, we are adding composite SQL non clustered index on Professional column, and Yearly Income column

CREATE NONCLUSTERED INDEX IX_CustomerRecord_ProfessionIncome
ON CustomerRecord ([Profession] DESC, [Yearly Income] ASC)
Messages
--------
Command(s) completed successfully.

Now you can see them.

Create Composite Non Clustered Index in SQL Server 8

Create Multiple Non Clustered Indexes in SQL Server

It allows you to create multiple non clustered indexes per table. In this example, we are adding non clustered index to Professional column, and another one on Yearly Income column

CREATE NONCLUSTERED INDEX IX_CustomerRecord_Profession
ON CustomerRecord ([Profession] ASC)

CREATE NONCLUSTERED INDEX IX_CustomerRecord_Income
ON CustomerRecord ([Yearly Income] DESC)
Messages
--------
Command(s) completed successfully.

Now you can see multiple

Create Multiple Non Clustered Indexes in SQL Server 10

Create Non Clustered Index in SQL Server Management Studio

Let me show you, how to create a non clustered index, how to delete it using Management Studio

Use Object Explorer to Create Non Clustered Index

In this example, we explain how to create a Non Clustered using the Management Studio.

To do so, please go to the Object Explorer and expand the Database folder. Please expand the table to create, and Right-click on the Indexes folder will open the context menu. Please select New and then select the Non-Clustered ..

New Index using Management Studio 11

Once you choose the option, a new window will be opened as we showed below. Please change the Name as per your requirements

Non Clustered Index in SQL Server 12

Click on the Add button, and select the column name on which you want to specify. For now, we are selecting the Last Name column.

Non Clustered Index in SQL Server 13

Please change the sort order.

Non Clustered Index in SQL Server 14

Now you can see it

Non Clustered Index in SQL Server 15

Using Table Designer

Please extend the table on which you require to create, and Right-click on it will open the context menu. Please choose the Design option to open the table in the Designer window.

Next, Right-click on the column and select the Set Indexes/Keys… option.

Non Clustered Index in SQL Server 16

Please click on the Add button to add a new. Once you select the Add option, SSMS will create an Index for you.

Non Clustered Index in SQL Server 17

Next, click on the Browse button beside the Columns option to change the column. Next, we selected the Profession as the Column Name, and Descending is the Sort Order.

Non Clustered Index in SQL Server 18

Under the Table Designer, Please change the Create As Clustered option to No

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See the newly created one

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Delete or Drop Non Clustered Index in SQL Server

Please use the DROP INDEX statement to delete or drop.

DROP INDEX CustomerRecord.IX_CustomerRecord_Profession
Messages
--------
Command(s) completed successfully.

Use Management Studio Example

Within the object explorer, Expand the Database folder and choose the table on which it present. Next, expand the Indexes folder, and right-click on the name will open the context menu. Please select the Delete option

Non Clustered Index in SQL Server 5

Once you select the Delete option, Delete Object window opened. Click OK to delete the Non clustered Index in SQL Server.

Non Clustered Index in SQL Server 6

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